Two trains of length 200 m and 100 m simultaneously writer - a tunnel ...
Given:
- Length of the first train = 200 m
- Length of the second train = 100 m
- Length of the tunnel = 300 m
- Speed of the first train = 36 kmph
- Speed of the second train = 18 kmph
To find:
- Time taken for the tunnel to be free of traffic again
Approach:
- We need to find the time taken for both trains to completely enter the tunnel.
- The train that enters the tunnel first will exit last, so we need to consider the time taken for the first train to completely enter the tunnel.
- We can calculate the time taken for the first train to completely enter the tunnel by dividing the length of the first train by the relative speed of the two trains.
- Once the first train completely enters the tunnel, the second train will still have to enter the tunnel completely.
- We can calculate the time taken for the second train to completely enter the tunnel by dividing the length of the second train by the relative speed of the two trains.
- The total time taken for the tunnel to be free of traffic again will be the maximum of the time taken for the first train to completely enter the tunnel and the time taken for the second train to completely enter the tunnel.
Calculation:
- Relative speed of the two trains = Speed of the first train - Speed of the second train = 36 kmph - 18 kmph = 18 kmph = 5 m/s
- Time taken for the first train to completely enter the tunnel = Length of the first train / Relative speed of the two trains = 200 m / 5 m/s = 40 s
- Time taken for the second train to completely enter the tunnel = Length of the second train / Relative speed of the two trains = 100 m / 5 m/s = 20 s
- Total time taken for the tunnel to be free of traffic again = Maximum of the above two times = max(40 s, 20 s) = 40 s
Therefore, the tunnel will be free of traffic again after 40 seconds.
Answer:
The tunnel will be free of traffic again after 40 seconds.